NETWORK RTK
A BRIEF HISTORY
Single Base RTK
During the 1990’s GPS RTK surveying started to become a real benefit to users. The concept was based on two GPS receivers, known as a “Base and Rover”. The set of receivers measured distances to the satellites, using the L1 & L2 carrier phase signals. The base station transmits it’s known position to the rover via a UHF radio. The rover then uses the base station position, together with its common set of satellite observations, to solve ambiguities and precisely compute its position to cm level accuracy. However, like most first generation technology the kit was large in comparison to today, with many batteries, cables, poles, tripods, backpacks and other accessories to carry around and set-up.
There can also be distance dependent limitations to the “base rover” method, where the accuracy degrades the further the rover moves away from the base station. This is mainly caused by an increase in atmospheric errors between the base and rover, which makes it harder for the rover to fix its position.
In its early inception, for many GPS or GNSS surveying was deemed as a “black art” and a highly scientific method, where the operator needed a high level of education, or even a degree in GPS surveying!
Traditional “base & rover” method of receiving RTK corrections. The base station is set-up on a known point and sends corrections to the rover, normally via a UHF radio link.
There can also be distance dependent limitations to the “base rover” method, where the accuracy degrades the further the rover moves away from the base station. This is mainly caused by an increase in atmospheric errors between the base and rover, which makes it harder for the rover to fix its position.
In its early inception, for many GPS or GNSS surveying was deemed as a “black art” and a highly scientific method, where the operator needed a high level of education, or even a degree in GPS surveying!
Traditional “base & rover” method of receiving RTK corrections. The base station is set-up on a known point and sends corrections to the rover, normally via a UHF radio link.
Tradition Single Base RTK
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Although the general method of setting up a base and rover is now well known, there are further disadvantages, such as;
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Network RTK
During the last decade a new method of Network RTK has evolved, and in the last five years it has matured as the de-facto standard for many GNSS applications.
Network RTK is based on a set of Continuously Operating Reference Stations (CORS), which could form a national or regional reference station infrastructure. GNSS satellite observations are continuously gathered from all the reference stations, and streamed to a central processing centre via the internet. All the observations are then used to model the entire network, which is now free from the distance dependent constraints of a traditional base & rover. At Topcon we use the state-of-the-art network software called TopNET+.
Network RTK is based on a set of reference stations continuously streaming GNSS observations to a control centre (TopNET+).
The distances between the reference stations may be as large as 70km and could span an entire country.
Network RTK is based on a set of Continuously Operating Reference Stations (CORS), which could form a national or regional reference station infrastructure. GNSS satellite observations are continuously gathered from all the reference stations, and streamed to a central processing centre via the internet. All the observations are then used to model the entire network, which is now free from the distance dependent constraints of a traditional base & rover. At Topcon we use the state-of-the-art network software called TopNET+.
Network RTK is based on a set of reference stations continuously streaming GNSS observations to a control centre (TopNET+).
The distances between the reference stations may be as large as 70km and could span an entire country.
TopNet Live Network RTK
Network RTK Subscriptions
Many Network RTK subscription services now exist throughout Europe and the world, such as the TopNET live service. Network RTK rovers are now widely used with subscriptions, such as the Topcon GRS-1, GRS-3, AGI3 etc..
Rover users working anywhere within the network boundary can connect to the TopNET live service (the TopNET+ server) via mobile internet connections (GSM, GPRS, 3G etc..) and will receive fully modelled Network RTK corrections.
Rover users working anywhere within the network boundary can connect to the TopNET live service (the TopNET+ server) via mobile internet connections (GSM, GPRS, 3G etc..) and will receive fully modelled Network RTK corrections.
There Are Many Advantages Of Network RTK, Such As:
- No need to purchase a base station
- No need to set-up and move a base station
- No security issues to protect the base station
- Modelled network corrections which provide a “constant” level of accuracy across the entire network coverage area
- Increased productivity using two rovers compared to a base & rover set
- All users are using a common coordinate system, normally linked directly to the national grid system
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There Are 4 Basic Steps To The Network Agency Management:
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